The present invention relates to keyboards, and more particularly to a keyboard in which acoustic energy is used to identify the actuation of individual keys.
In the past, various types of keyboards have been used for entering data into typewriters, sales terminals, computers and the like. The type of keyboard is generally designated by the particular switching mechanism which is used in its keyswitches. Mechanical switches providing electrical contact between conductive electrodes, reed switches utilizing a magnetic field to close conductive electrodes, Hall-effect switches, and capacitive switches have all been used in past keyboard designs. Such past keyboards require the use of printed circuit boards and/or electromechanical components, which can be expensive. Reliability of such past keyboards can be adversely affected by contamination of switch contacts, dirt, harsh environments, and the like.
It would be advantageous to have a keyboard which is simple to manufacture, relatively inexpensive, and at the same time more reliable than past keyboards. The present invention provides such a keyboard by using acoustic energy to detect keyswitch actuation.